Does the Volume of Amylase Affect the Rate of Reaction between Amylase and Starch?

Ph values

The variable I will be changing is the volume of amylase.

Safety:

To make sure I carry out this experiment safely I will make sure I wear goggles. I will ensure I keep my stool under the table and all bags and coats will be well out of the way.

Fair Test:

To make sure the experiment is a fair test I will only change the volume of amylase. All the other variables I will keep the same. I will also make sure that I keep my apparatus the same throughout the experiment.

Apparatus:

Colorimeter

Micro pipette

Iodine solution

Test tube

Amylase

Stopwatch

Measuring cylinder

Starch

Filter 470 (For the colorimeter)

Colorimetery:

A colorimeter will be used to measure the reaction rate between amylase and starch. It does this by measuring the light absorption of the solutions obtained and comparing them to a standard. To set the standard of the colorimeter, a cuvett with a substance in that has the same properties that is desired at the end of the experiment (In this experiment it will be distilled water), is placed in the colorimeter. The light absorption of this substance is measured and the machine is calibrated to this substance's light absorption reading. Now, when another substance is placed in the colorimeter, the colorimeter will display whether and when (if reaction is taking place) it has the same light absorption as the standard.

The colorimeter works by shining light through the standard and then measuring how much light travels through it. It is able to measure this by using photosensitive cells. The electricity generated by these due to the light travelling through the solution and on to the photosensitive cells is then measured and is converted into a unit suitable for a final reading (in this case light absorption).

The colorimeter is relevant as it will allow me to show clearly and accurately the rates of reaction of the different volumes of amylase. I enables me to do this by telling me the percentage light absorption of the different solutions which can then be compared on a graph.

Method:

Make sure that the colorimeter is set up and that is has been calibrated. Insert Filter 470 into the filter slot. Put 0.1cm³ of starch in a test tube. Add 0.01cm³ of iodine solution to the test tube. The contents will go blue/black. Add 4.0cm³ of amylase to the test tube. Immediately pour it into to a cuvett and place the cuvett into the colorimeter. Measure the reading on the colorimeter 11 times, once as soon as it is placed in the colorimeter and the following 10 times at intervals of 30 seconds.

Do this 6 times, increasing the volume of amylase by 1.0cm³ each time. The following volumes of amylase will be tested;

4.0cm³

5.0cm³

6.0cm³

7.0cm³

8.0cm³

9.0cm³

Repeat each volume of amylase 2 times and then work out an average.

Observation

Results Collected:

Analysis

Percentage Light Transmission Averages:

Rate of Reactions:

From my graphs it is visible that as the volume of amylase is increased the rate of reaction between the starch and amylase does not. All of the different volumes of amylase have different rates of reaction but none of them are different enough to warrant a conclusion.

Therefore my experiment does not support my prediction that as the volume of amylase increases so to will the rate of reaction. However, I don't think that this is because of the theory of my prediction but rather the method of my prediction. I still would predict that as the volume of amylase increases so to does the rate of reaction but I think that the volumes of amylase need to be larger and more different.

It can be seen from the graph that shows the average gradients (rates of reactions) that although there is negative correlation that the gradients are all very similar.

Evaluation

I think that the experiment went very well as far as method is concerned. However, I feel that there is one major change that needs to be made so that I can draw a conclusion from my results. I think the way that I performed the experiment could benefit from only minor changes. These changes mainly regard how time is managed. I carried out the experiment completely in accordance with my method (see page 3).

I think the suitability of the different volumes of amylase wasn't very good. I think that the range of volume needed to be larger which would have allowed for increasements between each individual volume of amylase. This would have given me a much better set of results which would have larger differences between the rates of reaction. This would have meant I could have drawn a conclusion and proved my prediction. I think that that if this experiment or any like it were repeated, then more thought needs to be put into this aspect of the method.

The experiment went very well and was accurate except the test 2 of 9.0cm³ (explained in the next paragraph). The use of the colorimeter really helped and aided me in making the experiment as accurate as possible. Another thing that benefited the accuracy of the experiment was the colorimeter we used. There were two different types; one which gave an analogue reading and one which gave a digital reading. I managed to use the one which gave a digital reading which significantly reduced the risk of human error because if I had used the one with the analogue reading I may have read the dial wrong.

The reason I think that the second test of 9.0cm³ of amylase went wrong is because I performed the experiment on different days. This could have meant that the room temperature was different. This could have affected the experiments results because enzymes work better when the temperature is hotter thus if the temperatures were different on the two days the experiment was carried out then the results will be different.

This brings me on to the time aspect. I think if I had had more time and was able to do my experiment on one day then my results may have been better as the temperature would have been the same.

I think overall the experiment went ok. Although I wasn't able to prove my prediction correct I feel that it is unproven rather than disproven. I fell that my method could be improved dramatically as stated above.

Biology TCW December 07

Biology Coursework 1/7 Tim Wroblewski